Burwick is 8.5 years old. He has always had a problem with throwing up food. Not often but now and again. What came up mostly looked like what went down, dry and not chewed. Because of this I always feed each meal in 2 parts with a small bit of exercise in between or maybe a walk. Then a drink of water. Lately I have noticed it is happening about 3 times a week. I feed Canidae dog food. Any ideas on my problem?